In recent years web-based systems such as Enterprise Information Portals have gained importance in many companies. Latter integrate, as a single point of access, various applications and processes into one homogeneous user interface.
Today, such systems are comprised of a huge amount of content. They are no longer exclusively maintained by an IT department instead, Web 2.0 techniques are used increasingly, allowing user generated content to be added. These systems grow quickly and in a more uncoordinated way as different users possess different knowledge and expertise and obey to different mental models.
The continuous growth makes access to really relevant information difficult. Users need to find task- and role-specific information quickly. Thus, users often miss out on resources that are potentially relevant to their tasks, simply because they never come across them. On the one hand, users obtain too much information that is not relevant to their current task, on the other hand, it becomes cumbersome to find the right information and they do not obtain all the information that would be relevant.
The recent popularity of collaboration techniques on the Internet, particularly tagging and rating, provides new means for both semantically describing Portal content as well as for reasoning about users' interests, preferences and contexts.
Tagging is the process of assigning keywords (or metadata) to resources. A tag itself is “some” metadata associated to a resource. Tags themselves are non-hierarchical keywords taken from an uncontrolled vocabulary. A resource is an entity uniquely identifiable (addressable).
Tags can add valuable meta-information and even lightweight semantics to web resources.
Rating is the evaluation or assessment of something, in terms of quality (as with a critic rating a novel), quantity (as with an athlete being rated by his or her statistics), or some combination of both. I.e. it is the process of assigning (e.g. numeric) “values” to resources indicating how much people “like” those. A rating itself is “some value” associated to a resource. Ratings themselves are chosen from an interval of possible “values” whereas the one end of the interval usually refers to “dislike” and the other to “like”.